Striking plate for a golf club head

ABSTRACT

A golf club having a club head with a striking plate that has an aspect ratio in excess of 0.575. The golf club head has a thin striking plate with a high aspect ratio in order to increase the deflection of the striking plate during impact with a golf ball. The striking plate may be composed of stainless steel, titanium, aluminum, amorphous metal, composites, or the like. The golf club head may be a wood or an iron.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation-in-part application ofco-pending U.S. patent application Ser. No., 09/475,752, filed on Dec.30,1999, which is a continuation-in-part application of co-pending U.S.patent application Ser. No. 09/454,695, filed on Dec. 3, 1999, which isa continuation application of U.S. patent application Ser. No.09/120,433 filed on Jul. 22, 1998 now U.S. Pat. No. 6,007,432, which isa continuation application of U.S. patent application Ser. No.08/735,601, filed on Oct. 23, 1996, now U.S. Pat. No. 5,830,084.

FEDERAL RESEARCH STATEMENT

[0002] Not Applicable

BACKGROUND OF INVENTION

[0003] 1. Field of the Invention

[0004] The present invention relates to a golf club head. Morespecifically, the present invention relates to a golf club head with astriking plate having a more circular aspect ratio.

[0005] 2. Description of the Related Art

[0006] When a golf club head strikes a golf ball, large impacts areproduced that load the club head face and the golf ball. Most of theenergy is transferred from the head to the golf ball, however, someenergy is lost as a result of the collision. The golf ball is typicallycomposed of polymer cover materials (such as ionomers) surrounding arubber-like core. These softer polymer materials having damping (loss)properties that are strain and strain rate dependent which are on theorder of 10-100 times larger than the damping properties of a metallicclub face. Thus, during impact most of the energy is lost as a result ofthe high stresses and deformations of the golf ball (0.001 to 0.20inches), as opposed to the small deformations of the metallic club face(0.025 to 0.050 inches). A more efficient energy transfer from the clubhead to the golf ball could lead to greater flight distances of the golfball.

[0007] The generally accepted approach has been to increase thestiffness of the club head face to reduce metal or club headdeformations. However, this leads to greater deformations in the golfball, and thus increases in the energy transfer problem.

[0008] Some have recognized the problem and disclosed possiblesolutions. An example is Campau, U.S. Pat. No. 4,398,965, for a MethodOf Making Iron Golf Clubs With Flexible Impact Surface, which disclosesa club having a flexible and resilient face plate with a slot to allowfor the flexing of the face plate. The face plate of Campau is composedof a ferrous material, such as stainless steel, and has a thickness inthe range of 0.1 inches to 0.125 inches.

[0009] Another example is Eggiman, U.S. Pat. No. 5,863,261, for a GolfClub Head With Elastically Deforming Face And Back Plates, whichdiscloses the use of a plurality of plates that act in concert to createa spring-like effect on a golf ball during impact. A fluid is disposedbetween at least two of the plates to act as a viscous coupler.

[0010] Yet another example is Jepson et al, U.S. Pat. No. 3,937,474, fora golf Club With A Polyurethane Insert. Jepson discloses that thepolyurethane insert has a hardness between 40 and 75 shore D.

[0011] Still another example is Inamori, U.S. Pat. No. 3,975,023, for aGolf Club Head With Ceramic Face Plate, which discloses using a faceplate composed of a ceramic material having a high energy transfercoefficient, although ceramics are usually harder materials. Chen etal., U.S Pat. No. 5,743,813 for a Golf Club Head, discloses usingmultiple layers in the face to absorb the shock of the golf ball. One ofthe materials is a non-metal material.

[0012] Lu, U.S. Pat. No. 5,499,814, for a Hollow Club Head WithDeflecting Insert Face Plate, discloses a reinforcing element composedof a plastic or aluminum alloy that allows for minor deflecting of theface plate which has a thickness ranging from 0.01 to 0.30 inches for avariety of materials including stainless steel, titanium, KEVLAR®, andthe like. Yet another Campau invention, U.S. Pat. No. 3,989,248, for aGolf Club Having Insert Capable Of Elastic Flexing, discloses a woodclub composed of wood with a metal insert.

[0013] Although the prior art has disclosed many variations of golf clubheads, the prior art has failed to provide a golf club head having astriking plate that increases the coefficient of restitution throughincreasing the depth of the striking plate.

SUMMARY OF INVENTION

[0014] The present invention provides a golf club head that is capableof imparting a very high coefficient of restitution. The presentinvention is able to accomplish this by using a striking plate having anincreased depth, and a predetermined stiffness.

[0015] One aspect of the present invention is a golf club head with astriking plate that has an aspect ratio in excess of 0.575. The strikingplate also has a depth within a certain range, and a width within acertain range. This allows the striking plate to have a greaterdeflection during impact with a golf ball thereby allowing for a greatertransfer of energy to the golf ball. This energy transfer results in agolf club having a high coefficient of restitution. The coefficient ofrestitution is measured under test conditions, such as those specifiedby the USGA. The standard USGA conditions for measuring the coefficientof restitution is set forth in the USGA Procedure for Measuring theVelocity Ratio of a Club Head for Conformance to Rule 4-1e, Appendix II.Revision I, Aug. 4, 1998 and Revision 0, July 6, 7998, available fromthe USGA.

[0016] Having briefly described the present invention, the above andfurther objects, features and advantages thereof will be recognized bythose skilled in the pertinent art from the following detaileddescription of the invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

[0017]FIG. 1 is a front plan view of a golf club of the presentinvention.

[0018]FIG. 2 is a top plan view of the golf club head of FIG. 1.

[0019]FIG. 3 is an isolated view of a striking plate for a golf clubhead of the present invention.

[0020]FIG. 4 is a cross-sectional view of the golf club head of FIG. 2along line 4-4.

[0021]FIG. 5 is an isolated view of the striking plate of FIG. 3.

[0022]FIG. 6 is an isolated view of a striking plate of the prior art.

[0023]FIG. 7 is an isolated view of an alternative embodiment of astriking plate of the present invention.

[0024]FIG. 8 is a front plan view of an alternative embodiment of a golfclub of the present invention.

[0025]FIG. 9 is an isolated view of an alternative embodiment of astriking plate of the present invention.

[0026]FIG. 10 is an isolated view of an alternative embodiment of astriking plate of the present invention.

[0027]FIG. 11 is an isolated view of an alternative embodiment of astriking plate of the present invention.

[0028]FIG. 12 is a side view of a golf club head of the presentinvention immediately prior to impact with a golf ball.

[0029]FIG. 13 is a side view of a golf club head of the presentinvention during impact with a golf ball.

[0030]FIG. 14 is a side view of a golf club head of the presentinvention immediately after impact with a golf ball.

[0031]FIG. 15 is a cross-sectional view of a golf club head of thepresent invention.

[0032]FIG. 15A is a representation of a striking plate simply supportedto illustrate one extreme of striking plate deflection during impactwith a golf ball.

[0033]FIG. 15B is a representation of a striking plate fixedly supportedto illustrate the other extreme of striking plate deflection duringimpact with a golf ball.

[0034]FIG. 16 is a representation of a striking plate to demonstrate thepossible increases in depth relative to a fixed width.

[0035]FIG. 17 is a representation of a striking plate to demonstrate agolf ball's impact force with the striking plate.

[0036]FIG. 18 is a graph of aspect ratio versus face dimensions.

[0037]FIG. 19 is a graph of uniform face weight versus face dimensions.

[0038]FIG. 20 is a graph of face stiffness versus face dimensions.

[0039]FIG. 21 is a graph of uniform face thickness versus facedimensions.

[0040]FIG. 22 is a graph of figure of merit.

DETAILED DESCRIPTION

[0041] The present invention is directed at a golf club head having astriking plate that is thin and has a high coefficient of restitutionthereby enabling for greater distance of a golf ball hit with the golfclub head of the present invention. The coefficient of restitution (alsoreferred to herein as COR) is determined by the following equation:

e=v₂ v₁ U₁ U₂

[0042] wherein U₁ is the club head velocity prior to impact; U₂ is thegolf ball velocity prior to impact which is zero; v₁ is the club headvelocity just after separation of the golf ball from the face of theclub head; v₂ is the golf ball velocity just after separation of thegolf ball from the face of the club head; and e is the coefficient ofrestitution between the golf ball and the club face.

[0043] The values of e are limited between zero and 1.0 for systems withno energy addition. The coefficient of restitution, e, for a materialsuch as a soft clay or putty would be near zero, while for a perfectlyelastic material, where no energy is lost as a result of deformation,the value of e would be 1.0. COR ranges refer to USGA test standards.The present invention provides a club head having a striking plate orface with a coefficient preferably in the range of 0.81 to 0.93, andmore preferably in the range of 0.82 to 0.85 as measured underconventional USGA test conditions.

[0044] As shown in FIGS. 1-4, a preferred golf club is generallydesignated 20. The golf club 20 has a club head 22 that is engaged witha shaft 24. A ferrule 26 encircles the shaft 24 at an aperture 27 to ahosel 29. The club head 22 has a body 28 and a striking plate 32. Thestriking plate 32 has a plurality of scorelines 34 thereon. The strikingplate 32 generally extends from a heel end 36 of the club head 22 to atoe end 38 of the club head 22. The body 28 has a crown 40 and a sole42. As shown in FIG. 4, the body 28 has a hollow interior 44. Positionedinside the hollow interior 44 is the hosel 29. The club head body 28 hasa volume preferably in the range of 250 cubic centimeters to 400 cubiccentimeters and more preferably in the range of 300 cubic centimeters to380 cubic centimeters.

[0045] The striking plate 32 is generally composed of a single piece ofmetal, and is preferably composed of a forged metal material. Morepreferably, the forged metal material is a forged titanium material.Such titanium materials include pure titanium and titanium alloys.However, alternative embodiments including steel such as stainless steelor steel alloys may also be used. Those skilled in the relevant art willrecognize that the face member may be composed of a number ofalternative embodiments such as vitreous metals, ceramics, composites,carbon, carbon fibers and other fibrous materials without departing fromthe scope and spirit of the present invention. The striking plate 32 hasa plurality of scorelines 34 thereon. The striking plate 32 may be castwith the body 28, or it may be welded to the body 28.

[0046] In an alternative embodiment, the striking plate 32 is composedof a vitreous metal such as iron-boron, nickel-copper, nickel-zirconium,nickel-phosphorous, and the like. These vitreous metals allow for thestriking plate 32 to have a thickness as thin as 0.055 inches. Yet infurther alternative embodiments, the striking plate 32 is composed ofceramics, composites or other metals. Additionally, the thinnest regionsof the striking plate 32 may be as low as 0.010 inches allowing forgreater compliance and thus a higher coefficient of restitution.

[0047] The striking plate 32 of the present invention has a largeraspect ratio than striking plates of the prior art. The aspect ratio asused herein is defined as the depth, D, of the striking plate 32 dividedby the width, W, of the striking plate, as shown in FIG. 3. The width,W, is measured between the farthest limits of the striking plate 32 fromthe heel end 36 to the toe end 38. The measured width, W, does notinclude any portion of the body 28 that may be on the front of the clubhead 22 but not part of the striking plate 32. The depth, D, is measuredfrom between the farthest limits of the striking plate 32 from the crown40 to the sole 42. As with the width, W, the depth, D, does not includeany portion of the body 28 that may be on the front of the club head 22but not part of the striking plate 32.

[0048] In one embodiment, the width W is 3.35 inches and the depth D is2.0 inches giving an aspect ratio of 0.6. In conventional golf clubheads, the aspect ratio is usually much lower than 0.6. For example, theoriginal GREAT BIG BERTHA® driver had an aspect ratio of approximately0.525 for its striking plate. The striking plate 32 of the presentinvention has an aspect ratio that is greater than 0.575. The aspectratio of the present invention preferably ranges from 0.575 to 0.8, andis most preferably from 0.6 to 0.7. The aspect ratio of the strikingplate 32 will be described in greater detail below.

[0049] As shown in FIGS. 4, 5 and 6, the thickness, “T”, of the strikingplate 32 may be uniform or it may be contoured as set forth in U.S. Pat.No. 6,007,432 for a Contoured Golf Club Face, which relevant parts arehereby incorporated by reference. However, unlike the striking plate 32′of the prior art (as shown in FIG. 6), the striking plate 32 has athickness, T, that is thinner providing for greater deflection of thestriking plate 32 during impact with a golf ball. In a contouredstriking plate 32, the thickness varies from a first thickness T1 to atleast a second thickness T2. The thickness, T, of the striking plate 32in relation to the aspect ratio is preferably in the range of 0.050 inchto 0.130 inch and is more preferably in the range of 0.100 to 0.110.

[0050] A golf club head 22′ is an alternative embodiment of the presentinvention. In this embodiment, the striking plate 32 a has a much morecircular aspect ratio. In this embodiment, the aspect ratio isapproximately 0.8. FIGS. 9-10 illustrate various types of strikingplates 32 b, 32 c and 32 d, respectively, that may be utilized with thepresent invention. The striking plate 32 b of FIG. 9 has a traditionalor conventional shape. The striking plate 32 c of FIG. 10 has anon-conventional oval shape with symmetry about an imaginary centralaxis through point 47. The striking plate 32 d of FIG. 11 has aninverted shape from the conventional shape of FIG. 9. Although severalshapes of striking plates have been illustrated, those skilled in thepertinent art will recognize that striking plates having other shapesare within the scope and spirit of the present invention.

[0051] As shown in FIGS. 12-14, the flexibility of the striking plate 32allows for a greater coefficient of restitution thereby increasing theperformance of the golf club 20. At FIG. 12, the striking plate 26 isimmediately prior to striking a golf ball 140. At FIG. 13, the strikingplate 26 is engaging the golf ball 140, and deformation of the golf ball140 and striking plate 26 is illustrated. The striking plate 26 isallowed to deflect about the golf ball 140 thereby lessening thedeformation of the golf ball 140 relative to prior art. The golf ball140 is also engaged with the striking plate 26 for a longer period oftime due to the deflection of the striking plate. This longer engagementperiod leads to a greater transfer of energy from the golf club to thegolf ball thereby increasing the coefficient of restitution. At FIG. 14,the golf ball 140 has just been launched from the striking plate 26.

[0052]FIG. 15 illustrates the striking plate 32 and the plurality ofscorelines 34. Each of the plurality of scorelines 34 may act as astress concentrator during impact with a golf ball. Like other strikingplates of the prior art, the striking plate 32 of the present inventionis positioned between the crown 40 and sole 42. During impact with agolf ball, the striking plate 32 will deflect depending upon theconnection to the crown 40 and the sole 42. FIGS. 15a and 15B illustratethe extremes of such connection, and thus every golf club striking platethat is connected to the crown and the sole should fall within these twoextremes. FIG. 15A illustrates a striking plate 32 e that is simplysupported on two beams 51 a and 51 b. Such a simple support structurewill allow each edge of the striking plate 32 e to rotate during impactwith a golf ball 140 and deflect as shown by dashed lines 32 e′.However, each edge of the striking plate 32 e is fixed from translation.At the other extreme is the striking plate 32 f of FIG. 15b, which isessentially clamped between beams 51 c and 51 d. Depending upon thespeed at impact with a golf ball, the fixed striking plate 32 f willdeflect as shown by dashed lines 32 f′. However, each edge of thestriking plate 32 f is fixed from translating and rotating. The strikingplates 32 of the present invention are closer to the simple supportstructure than to the fixed structure.

[0053]FIG. 16 illustrates possible elliptical shapes 57, 59, 61, 63 and65 that a striking plate 32 g may have by increasing the depth, D, alongthe y-axis while holding the width, W, constant. The half-width distance“a” (a=W/2) is usually constant for most golf clubs, however, thehalf-depth distance, “b” (b=D/2), has been limited to relatively smallvalues. The present invention increases b relative to the prior art tocreate a striking plate 32 with a more circular aspect ratio. The aspectratio, α=b/a, varies between zero and one, with one being a circle. Thepresent invention, as mentioned previously, has a striking plate 32 withan aspect ratio of at least 0.575. The striking plate 32 of the presentinvention is able to achieve greater flexibility and thus improve energytransfer to the golf ball during impact by increasing the aspect ratioof the striking plate 32.

[0054] The weight or mass of the striking plate 32 linearly increases asthe aspect ratio increases as set forth in the following equation:mass=ρπTa²α wherein p is the weight or mass density of the material, Tis the thickness of the striking plate 32, a is the half-width of thestriking plate 32, and α is the aspect ratio. Thus, the striking plate32 should be thinner as the aspect ratio increases in order to avoid aheavy golf club.

[0055]FIG. 17 illustrates the force against a striking plate 32 duringimpact with a golf ball. During impact with a golf ball, a uniform load,as shown by circle 99, will be applied to the striking plate 32, asshown by force lines 101. The force circle 99 has a radius of r_(o) ,which ranges between 0.3 and 0.60 inches. Typical impacts of a driverwith a golf ball will result in a force, F, ranging from 1500 to 2500pounds per square inch. The force of impact is given by the equation:F = ∫₀^(2π)∫₀^(r_(o))qr  r  θ

[0056] where q is the pressure distribution over the impact area. Thedisplacement of the simple support structure of FIG. 15A is given by thefollowing equation:

Δ=Fa²α²/Et³(0.76−0.18α)

[0057] wherein E is the Young's Modulus for the material of the strikingplate 32. The displacement of the fixed support structure of FIG. 15B isgiven by the following equation:

Δ=Fa²α²/Et³(0.326−0.104α)

[0058] wherein E is the Young's Modulus for the material of the strikingplate 32. To increase the displacement, Δ, of the striking plate 32during impact for a given golf ball impact load, F, one may increase a,reduce E, decrease t or increase α. Modifying t or α will have thegreatest effect on the displacement, however, t is controlled by thematerials as described below.

[0059] The effective stiffness at the center of the striking plate 32 isgiven by the equation:

K_(eff)=F_(center)/Δ_(center)=Et³/a²α²(0.76−0.18α)

[0060] for the simple structure, and

K_(eff)=F_(center)/Δ_(center)=Et³/a²α²(0.326−0.104α)

[0061] for the fixed structure. Therefore, to decrease stiffness, oneshould reduce T, increase a, use a material with a lower E, or increaseα. Thus, the stiffness of the striking plate 32 is altered by increasingthe aspect ratio thereby by allowing for greater deflection of thestriking plate during impact with a golf ball.

[0062] The stress at the center of the striking plate 32 during impactwith a golf ball is given by the equations:

σ=3F(1+v)/2πt²[{In (2b/r0)−0.317α−0.376}] for the simple structure and

σ=3F/2πt²[{(1+v) In (b/r0)+v(6.57−2.57α)}] for the fixed structure,

[0063] where (v) is the Poisson ratio of the striking plate 32 material.Solving for the minimum required thickness gives the followingequations:${T = \sqrt{\frac{3F^{*}}{2\pi \quad \sigma_{yeild}}\left\lbrack {{\left( {1 + v} \right){\ln \left( \frac{b}{r_{0}} \right)}} + {v\left( {6.57 - {2.57\alpha}} \right)}} \right\rbrack}},$

[0064] for the simply-supported case and${T = \sqrt{\frac{3{F^{*}\left( {1 + v} \right)}}{2\pi \quad \sigma_{yeild}}\left\lbrack {{\ln \left( \frac{2b}{r_{0}} \right)} - {{.317}\alpha} - {.376}} \right\rbrack}},$

[0065] for the fixed edge support case, where (σ_(yield)) is thestrength of the striking yield plate 32 material, F* is the effectiveimpact force that includes the effects of design safety factors andscoreline stress concentration factors and ranges between 2000 and15,000 pounds for the striking plate 32 of the present invention.

[0066] The half-width, a, is between 1.25 and 2.0 inches for thestriking plate 32 of the present invention. The aspect ratio, α, isbetween 0.575 and 1.0 for the striking plate 32 of the presentinvention. Other values for materials of the striking plate 32 are setforth in Table One. TABLE One ρ ρ Ε σ yield (weight density) Material10⁶ lb/in² ν 10³ lb/in² lb/in³ density) grams/in³ Stainless Steel 290.27 150 0.28 126.93 Titanium (6-4) 16.5 0.31 115 0.16 72.53 Aluminum 100.333 73 0.101 45.78 Maraging Steel 28.4 0.3 280 0.28 126.93 LiquidMetal 13.3 0.3 260 0.22 99.73

[0067] FIGS. 18-22 demonstrates the features of the striking plate 32 ofthe present invention in light of prior art. The boxes on the graphsrepresent the prior art, and where these prior art golf club strikingplates are positioned in relation to each other and the striking plate32 of the present invention. Persimmon is a persimmon wood golf club ofthe prior art. GBB is a GREAT BIG BERTHA® driver available from CallawayGolf, BBB is a BIGGEST BIG BERTHA ® driver available from Callaway Golf,Orlimar is a Tri-Force driver from Orlimar Golf, Scud and Marumenrepresent drivers from these Japanese companies.

[0068]FIG. 18 illustrates the aspect ratio of the striking plate versusthe face dimensions of the striking plate. Lines 200-204 representaspect ratio lines. The prior art golf club striking plates lie below anaspect ratio line of 0.575. The striking plates 32 of the present lie ator above an aspect ratio line of 0.575.

[0069]FIG. 19 illustrates the weight or mass of a uniform thicknessstriking plate 32 versus the face dimensions. Lines 220-231 are lines ofequal weight or mass. Generally, the striking plate of the presentinvention has a mass that is within lines 222 and 228, or in otherterms, between 35 grams and 70 grams.

[0070]FIG. 20 illustrates the face stiffness versus the face dimensions.Lines 240-245 represent lines of equal stiffness. The striking plate 32of the present invention has a face stiffness between lines 244 and 245.

[0071]FIG. 21 illustrates face thickness and scorelines versus facedimensions. Lines 250-255 represent equal lines of face thickness. Thestriking plate 32 has a thickness in the range of 0.135 inches and 0.145inches.

[0072]FIG. 22 illustrates figure of merit which is face stiffness,multiplied by face mass versus the face dimensions. Lines 260-263represent lines of equal merit. The present invention has a figure ofmerit in excess of 40.

[0073] Thus, using aspect ratio, stiffness, material properties, and thelike, a golf club head of the present invention is designed to havegreater deflection which results in a greater transfer of energy to agolf ball during impact thereby increasing the coefficient ofrestitution of the golf club head, and allowing for the golf ball totravel further.

[0074] From the foregoing it is believed that those skilled in thepertinent art will recognize the meritorious advancement of thisinvention and will readily understand that while the present inventionhas been described in association with a preferred embodiment thereof,and other embodiments illustrated in the accompanying drawings, numerouschanges, modifications and substitutions of equivalents may be madetherein without departing from the spirit and scope of this inventionwhich is intended to be unlimited by the foregoing except as may appearin the following appended claims. Therefore, the embodiments of theinvention in which an exclusive property or privilege is claimed aredefined in the following appended claims.

I claim as my invention:
 1. A golf club head comprising: a body having aheel end and a toe end wherein a striking plate is disposed on the bodyand extends from the heel end to the toe end, wherein the striking plateis composed of a forged titanium material having an exterior surfacewith a depth, D, of the striking face ranging from 1.45 inches to 2.50inches and a width, W, ranging from 2.50 inches to 4.00 inches, whereinthe striking plate has an aspect ratio of at least 0.575, and a strikingface thickness, T, ranging from 0.050 inch to 0.130 inch, and whereinthe club head body has a volume ranging from 250 cubic centimeters to400 cubic centimeters and wherein the club has a coefficient ofrestitution ranging from 0.81 to 0.93 as measured under conventionalUSGA test conditions.
 2. The golf club head according to claim 1 whereinthe striking plate is composed of a forged steel material.
 3. The golfclub head according to claim 1 wherein the striking plate has athickness, T, in the range of 0.100 inch to 0.110 inch.
 4. The golf clubhead according to claim 1 wherein the club head body has a volume in therange of 300 cubic centimeters to 380 cubic centimeters.
 5. The golfclub head according to claim 1 wherein the club has a coefficient ofrestitution in the range of 0.82 to 0.85.
 6. A golf club headcomprising: a body having a heel end and a toe end wherein a strikingplate is disposed on the body and extends from the heel end to the toeend, wherein the striking plate is composed of a forged titaniummaterial having an exterior surface with a depth, D, of the strikingface ranging from 1.45 inches to 2.50 inches and a width, W, rangingfrom 2.50 inches to 4.00 inches, wherein the striking plate has anaspect ratio of at least 0.575, and a striking face thickness, T,ranging from 0.100 inch to 0.110 inch, and wherein the club head bodyhas a volume ranging from 300 cubic centimeters to 380 cubic centimetersand wherein the club has a coefficient of restitution ranging from 0.82to 0.85 as measured under conventional USGA test conditions.
 7. The golfclub head according to claim 6 wherein the striking plate is composed ofa material selected from the group consisting of steel, stainless steel,steel alloys, vitreous metals, ceramics, composites, carbon materials,carbon fiber materials, other fibrous materials and mixtures thereof.